Hello, I tried to build the regex library from Boost 1.32.0 with the Microsoft Visual C++ 7.1 compiler and without native wchar_t support. Below is the call to bjam: bjam -sTOOLS=vc-7_1 "-sBUILD=<native-wchar_t>off" --with-regex The build results of the dynamic link library (DLL) shows the following linker errors: Creating library bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi\boost_regex-vc71-mt-gd-1_32.lib and object bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi\boost_regex-vc71-mt-gd-1_32.exp instances.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) winstances.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) regex.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) regex_debug.obj : error LNK2019: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) referenced in function "void __cdecl regex_lib_print_compiler_macros(void)" (?regex_lib_print_compiler_macros@@YAXXZ) w32_regex_traits.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) wide_posix_api.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) c_regex_traits.obj : error LNK2019: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) referenced in function "public: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::syntax_type(unsigned int)const " (?syntax_type@?$cpp_regex_traits@_W@boost@@QBAII@Z) c_regex_traits_common.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) cregex.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) posix_api.obj : error LNK2001: unresolved external symbol "private: unsigned int __cdecl boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABAII@Z) bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi\boost_regex-vc71-mt-gd-1_32.dll : fatal error LNK1120: 1 unresolved externals ...failed vc-Link bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi\boost_regex-vc71-mt-gd-1_32.dll bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi\boost_regex-vc71-mt-gd-1_32.lib... ..skipped <@boost!lib>boost_regex-vc71-mt-gd-1_32.dll for lack of <@boost!libs!regex!build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi>boost_regex-vc71-mt-gd-1_32.dll... ...skipped <@boost!lib>boost_regex-vc71-mt-gd-1_32.lib for lack of <@boost!libs!regex!build\boost_regex.dll\vc-7_1\debug\native-wchar_t-off\threading-multi>boost_regex-vc71-mt-gd-1_32.lib... The build of the static library succeeds. Do I have to define a special macro, if I want to build regex without native wchar_t support? Or do the regex library support both, native wchar_t support and the mapping to unsigned short? In the header regex_traits.hpp I saw some wrappers to "redirects calls to cpp_regex_traits<unsigned short> to cpp_regex_traits<__wchar_t>". Regards, Jochen.